Abstract [en]

Thin (Na,K)NbOx perovskite films (NKN) have been deposited on SiO2/Si(0 0 1) substrates at low temperatures, from 350°C to 550°C, by RF magnetron sputtering. The effects of substrate temperature on microstructure, electrical-, and mechanical properties of the NKN films have been studied. X-ray diffraction analysis revealed that films deposited at temperatures in the range of 450–550°C were crystalline, growing as a single phase, with a preferred orientation of (0 0 1). Films deposited at 350°C, were shown to be amorphous. The growth temperature had a strong influence on the electrical properties of the NKN films and the relative dielectric constants of the obtained films were in between 38 and 78. Variations of the mechanical properties of the NKN films were observed for different substrate temperatures: The elastic moduli and the hardness values ranged from 205±26 to 93±29 GPa, and from 12±2 to around 2 GPa, for films deposited at 550°C and 450°C, respectively.

Abstract [en]

(a) Thin films of the perovskite structured Na0.5K0.5NbO3 (NKN) have been synthesised with several different sol-gel methods. Only one method gave pure NKN phase while the other methods gave extra peaks in the x-ray diffraction patterns, indicating that other, unidentified, phases were present. Scanning electron microscopy revealed grain sizes ranging from about 50 to 300 nm. The films prepared by chemical methods are compared with sputtered thin films.

(b) Nanocrystals of Gd2O3 have been prepared by various methods, using e.g. trioctylphosphine oxide (TOPO), diethylene glycol (DEG). The crystalline particles were of sizes 5 to 15 nm. Onto the surface of the particles, made with DEG, different carboxylic acids e.g. oleic acid or citric acid etc, were adsorbed. From IR measurements the bonding to the surface is recognised as chemisorbed via the carboxylate group in a bidentate or bridging fashion, with preference for the bridging coordination. The organic acid-particle complexes were characterised by XRPD, TEM, FTIR, Raman and XPS.